Doc #78933 [Opn]: gc_collect_cycles() may need a second pass when destructors are used

Edit report at https://bugs.php.net/bug.php?id=78933&edit=1 ID: 78933 Updated by: nikic@php.net Reported by: requinix@php.net Summary: gc_collect_cycles() may need a second pass when destructors are used Status: Open Type: Documentation Problem Package: *General Issues Operating System: Any (Windows?) PHP Version: 7.4.0 Block user comment: N Private report: N New Comment: For PHP 8.1, I have added an automatic GC re-run for destructed objects in https://github.com/php/php-src/commit/b58d74547f7700526b2d7e632032ed808abab442. Previous Comments: ------------------------------------------------------------------------ [2021-06-09 10:36:27] cmb@php.net Related To: Bug #81117 ------------------------------------------------------------------------ [2019-12-09 16:11:58] cmb@php.net > As far as I know, this is only possible to do on Windows since > Linux is supposed to allow deleting files with open handles. FWIW, as of PHP 7.3.0, files opened by the engine can also be deleted on Windows if they have open handles. That doesn't apply to SQLite3 databases, though. ------------------------------------------------------------------------ [2019-12-09 08:40:46] nikic@php.net Related To: Bug #78930 ------------------------------------------------------------------------ [2019-12-09 07:56:25] nikic@php.net Assuming the destructor doesn't do anything to make the object non-GCable, I believe that two runs should be sufficient. > Or perhaps a new optional "bool $repeat = true" argument to do that automatically? In reference to the original issue with PDO SQLite: No, I don't think this makes sense. Generally, manual GC runs should not be necessary to influence program behavior. I think this is an indication that PDO needs a way to explicitly close a connection that does not require destroying the object. I believe this was rejected in the past "because you can just write unset($pdo)", but in the presence of circular references this just isn't reliable. ------------------------------------------------------------------------ [2019-12-08 22:12:54] requinix@php.net Yes it does. Could it ever need more than two? If so, that would suggest using it like while (gc_collect_cycles()); Or perhaps a new optional "bool $repeat = true" argument to do that automatically? ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at https://bugs.php.net/bug.php?id=78933 -- Edit this bug report at https://bugs.php.net/bug.php?id=78933&edit=1